[gegl] buffer: reintroduce zeroing of scratch buffer allocation

[Øyvind Kolås <ok src gnome org>]

commit 47a52b8f59b973c31d9af7a10859b2340926db8c
Author: Øyvind Kolås <pippin gimp org>
Date:   Mon Oct 19 14:04:58 2015 +0200

    buffer: reintroduce zeroing of scratch buffer allocation
    
    Without this, valgrind complains about accessing uninitialized memory, this is
    pixels around the edges of the scratch buffer - for some babl conversions this
    also leads to horizontal/vertical line trails around brushes moving over the
    image. Further investigation into whether a manual clearing of this or
    avodiding the computations at the edges are faster would be nice.

 gegl/buffer/gegl-buffer-access.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/gegl/buffer/gegl-buffer-access.c b/gegl/buffer/gegl-buffer-access.c
index 3d083fb..fc7c190 100644
--- a/gegl/buffer/gegl-buffer-access.c
+++ b/gegl/buffer/gegl-buffer-access.c
@@ -1471,7 +1471,7 @@ _gegl_buffer_get_unlocked (GeglBuffer          *buffer,
           offset = (buf_width + 1) * bpp;
         }
 
-      sample_buf = g_malloc (buf_height * buf_width * bpp);
+      sample_buf = g_malloc0 (buf_height * buf_width * bpp);
       gegl_buffer_iterate_read_dispatch (buffer, &sample_rect,
                                          (guchar*)sample_buf + offset,
                                          buf_width * bpp,